I thought the Early 2015 MBP was still supported until Fall 2024. So it should be still be fine.

That said is is really easy to replace the battery yourself if you can follow a guide. And I do think it is fine for Apple to drop support on a laptop after 9 years.

Because you are using less channels. Bigger doesn’t always mean better.

You will actually get a better single where you are then using the same area as everyone else which will just cause co-channel interference.